I lived in Paris in 1999 and experienced the day of car-free Paris. It was nice--tons of cyclists of all different types and bikes. The air was cleaner and the city was QUIET! Parisian cagers love to toot their horns at every opportunity. I'll follow the the Mayor's plans to see how it turns out.
I did not have a car when I lived there, but I did drive a rental once. It was a bit exhilerating, but I wouldn't want to do it on a regular basis. Not until I drove in Naples, Italy did I yearn for the calm traffic of Paris.